一种利用平均周期间距和天体测量获取白矮星基本参数的星震技术
A Seismic Technique for Obtaining White Dwarf Fundamental Parameters from Mean Period Spacings and Astrometry
AI总结：
本研究提出一种结合Gaia天体测量与平均脉动周期间距的星震技术，可打破传统星震拟合的参数简并，得到白矮星可靠的质量与有效温度，为光谱方法提供互补约束，并已在WD 0158-160上验证有效。
AI中文摘要：
我们提出了一种新的统计技术，该技术结合现代空间任务提供的高精度天体测量数据与时序测光数据的协同作用，以获取脉动白矮星可靠的物理参数。我们计算了一组覆盖氦大气脉动白矮星（DBV）不稳定带的白矮星结构模型网格，结果表明，相邻脉动模式之间的平均周期间距，以及由Gaia天体测量数据推导的绝对星等，在参数空间内呈单调变化且变化方向相反。\n此前大多数白矮星星震学研究直接将单个脉动周期与恒星模型拟合，往往得到简并且分辨率较差的解；而当检测到可靠的平均周期间距时，这种“星震技术”能够针对质量、有效温度等全局参数给出唯一且可靠的星震解。我们的模型基于现代演化模型，采样了多种物理上合理的内部化学成分剖面，以传递实际恒星精细结构带来的不确定性。\n一旦全局恒星参数被严格约束，通过星震学解析白矮星内部结构的计算难度将大幅降低，参数简并问题也能得到解决。这种新星震技术对广泛使用的光谱技术所解析的精确吸收线轮廓不敏感，因此能够提供互补的约束条件，可用于检验光谱方法。我们针对TESS观测到的脉动氦大气白矮星WD 0158-160验证了该方法，得到有效温度$T_\mathrm{eff} = 24584\pm 971$ K，恒星质量$M_\star = 0.608\pm 0.013$ $M_\odot$。
英文摘要：
We present a new statistical technique that utilizes the synergy of precision astrometry and time series photometry from modern space missions to obtain reliable physical parameters of pulsating white dwarf stars. We compute a grid of white dwarf structural models that span the helium-atmosphere pulsating white dwarf (DBV) instability strip, showing that mean period spacings between adjacent pulsation modes and absolute magnitudes derived from Gaia astrometry vary monotonically and in opposing directions across parameter space. While most efforts in white dwarf asteroseismology to directly fit individual pulsation periods to stellar models result in degenerate and poorly resolved solutions, the "seismic technique" produces unique and reliable seismic solutions for global parameters of mass and effective temperature when a reliable mean period spacing is detected. Our models sample various physically plausible interior chemical composition profiles based on modern evolutionary models to propagate uncertainty from the precise structures of actual stars. Once the global stellar parameters are tightly constrained, seismically resolving white dwarf interior structures becomes more computationally tractable, and degeneracies can be resolved. This new seismic technique is largely insensitive to the precise absorption line profiles interpreted by the widely used spectroscopic technique, and therefore provides complementary constraints that can be used to test spectroscopic methods. We demonstrate the method for the pulsating helium-atmosphere white dwarf WD 0158-160 observed by TESS, obtaining $T_\mathrm{eff} = 24584\pm 971$ K and $M_\star = 0.608\pm 0.013$ $M_\odot$.
